1. Technical Field
The present invention relates to a communication system and a portable machine, and in particular to a communication system and a portable machine which are related to respective three nodes of a controlled object such as a vehicle, a portable machine, and a portable terminal.
2. Related Art
Currently, systems are generally known, in which a vehicle portable machine (hereinafter, referred to as an “FOB”) of a vehicle user communicates with a vehicle through radio waves. Existing portable terminals, such as portable phones or smartphones, are equipped with a function of relatively short-distance communications, including Bluetooth™ and Near Field Communication (NFC). With this function, wireless communications are widely conducted between a portable terminal and a vehicle or an FOB (for example, see JP 4496511 B1).
Such a wireless communication function is also used to acquire information from a vehicle or operate the vehicle.
For example, U.S. Pat. No. 7,821,383 discloses a technique in which a portable terminal acquires various information regarding a state of a vehicle, such as a voltage drop of a battery, or someone's intrusion into the vehicle, and displays the acquired information on the screen.
JP 2007-046395 A discloses a vehicle information setting device, which conducts wireless communications with a vehicle by using a portable phone as an interface through an FOB, and displays information regarding the vehicle. In addition, the vehicle information setting device is configured to set and control on-board apparatuses (for example, locking or unlocking of the doors).
Unfortunately, there are cases where the communication apparatus, such as an FOB or a portable terminal, communicates with the partner more than necessarily when both a communication apparatus and its partner are present within areas which electromagnetic waves reach. In this case, the communication apparatus may consume unnecessary electricity.
In consideration of such disadvantage, for example, JP 2010-130310 A discloses a communication device that aims to decrease the electricity consumption. The communication device is configured to transmit attribute information regarding a communication capacity thereof, and in turn receive attribute information regarding a communication capacity of a target. If the received attribute information indicates that the target is equipped with a communication function in a power saving mode, the communication device turns off the emission of an electromagnetic wave over a predetermined period after transmitting data.
JP 2010-028753 A discloses a communication device that aims to decrease the electricity consumption for proximity wireless communications. The communication device includes a proximity wireless communication device and an approaching detection unit that has lower electricity consumption than the proximity wireless communication device in an idle state. Then, the approaching detection unit detects a proximity state of another proximity wireless communication device or a removal from the proximity state thereof. When this proximity position state is detected, the communication device causes the proximity wireless communication device to be restored from a sleep state. Meanwhile, when the removal of the proximity state is detected, the communication device causes the proximity wireless communication device to enter the sleep state. Thus, the communication device causes the proximity wireless communication device to operate only when the proximity state is detected.
JP 06-131590 A discloses a movable body identification device that completes communications with a response unit moving at a high speed with a single communication sequence, and therefore does not more than necessarily conduct communications. In the movable body identification device, when the response unit enters a beam area of a question unit and receives an activation command, it transmits an activation response to the question unit. In turn, when receiving this activation response, the question unit transmits an operation command. When receiving the operation command, the response unit performs a predetermined operation, and then transmits an operation response. After that, the response unit receives a termination command indicating the termination of a series of communication sequences, and then enters a reception inhibition state over a predetermined period.
WO 2006/090460 A discloses a portable information terminal, which is a portable communication apparatus such as a portable phone and which enables application software to be activated through a simple user's operation. The portable information terminal is equipped with a reader (receiver) of a wireless IC tag. When being placed near the wireless IC tag, the portable information terminal reads information from the wireless IC tag. Then, the portable information terminal automatically activates an application related to this information, and displays it on the screen.
In many cases, however, an FOB and a portable terminal are held together, for example, in a user's pocket or bag. In such cases, an FOB and a portable terminal are likely to establish communications regardless of a user's intention and a screen of the portable terminal is maintained in an ON state. As a result, the unnecessary electricity may be consumed.